Process for manufacturing turbine bucket-wheels.



J. WILKINSON. PROCESS FOR, MANUFACTURING TURBINE BUCKET WHEELS.

APPLICATION FILED MAR. 20, 1906.

1,005,736; Patented 0ct.10,1911.

d nozwtoz super-fluid condition of the molten metal the wheel, and itmay be finally finished and balanced in one operation.

UNITED STATES PATENT OFFICE.

JAMES 'WILKINSON, OF PROVIDENCE, RHODE ISLAND, ASSIGNOR, BY MESNEASSIGN- MENTS, T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.v

emmas.

Specification of Letters Patent.

Patented Oct. 10, 1911 Application filed March 20, 1906. Serial No.307,089.

To all whom it may concern.

Be it known. that I, JAMES WILKINSON, a citizen of the United States,residing at Providence, in the county of Providence and State of RhodeIsland, have invented new and useful Improvements in Processes forManufacturing Turbine Bucket-Wheels, of which the following is aspecification.

My invention relates to an improved process for manufacturing bucketwheels for elastic fluid turbines, its object being to eliminate thelabor and cost of fitting or joining the buckets or vanes to the wheelblank. I propose to cast a disk wheel around the drilled or notchedinner ends of a ring of buckets and afterward to finish the wheel afterthe buckets have been thus joined thereto.

In practice. I provide positive means to hold the ring of buckets firmlyin position after which I ram sand around the buckets forming a bucketmold from which the inner ends of the buckets project. The bucket mold,after being packed, is then placed in the wheel mold and molten metal,treated to make it highly fluid, is introduced, suitable risers beingprovided to retard cooling of metal at the rim and to avoid shrinkstrains. The buckets may have their inner ends perforated or otherwiseprepared to cause them to be firmly rooted. in the wheel rim independentof any welding efiect, and, where the nature of the metals used requiresit, these ends will be coated with a flux.

As the preferred means for inducing a in the ladle, I use what iscommonly known as thethermit proicess. This process produces a veryrapid and violent reaction in the body of molten metal, serving tomate-' rially increase its fluidity without greatly raising itstemperature. In th1s highly fluid state the metal will flow read 1ly andrapidly throughout the mold, filling the latter uniformly and flowingaround the ex posed bucket ends so as to join the buckets with greatstrength and rigidity to the.

wheel at the time it is cast. By this "means I avoid having to fit orjoin the buckets to My invention further comprises the provision ofstems or projections at the outer ends of the buckets which are squaredor rated shroud or band, the stems projecting through the perforationsand riveted over to serve as a holding means.

My invention further comprises the improvements in the process formanufacturing wheels hereinafter more particularly described, in which:-

Figure 1, is a vertical sectional view through a completed mold readyfor casting the wheel blank to the buckets. Fig. 2, is an enlargedcross-sectional view of the bucket core and clamping ring. Fig.3, is apartial plan view of the bucket core with the sand and upper ring partlybroken away. Fig. 4, is an inside view of asection of. the clamping ringwith the buckets in position therein. Fig. 5, illustrates a sectionthrough the rim of a completed wheel. Fig. 6, illustrates the thermitprocess for treating the metal before pouring it into the mold.

Similar reference numerals refer to similar parts throughout thedrawings.

In carrying my improved process for manufacturing bucket wheels intoeffect, I first provide the requisite number of buckets 1, which arepreferably of nickel steel cut from a strip of the desiredcross-sectional contour and provided at their inner ends with one ormore holes 2, drilled or punched therethrough, and at their outer endswith integral projecting stems 3 having flat sides.

A set of these buckets have their stems 3 core oven and baked, afterwhich it is re-- moved and the inwardly projecting ends of the bucketsare cleaned and covered with a fiuxing composition to insure a free flowof metal around the bucket surface. As illuswith any suitable metal. Thewheel mold is then prepared by providing a cope 9 and drag 10 in whichthe sand is pressed around the pattern of the wheel blank or the moldmay be formed by a'sweep, allowance being made for the reception of theclamping ring the wheel, the metal would not remain sufliciently fluidthroughout the mold to properly unite all the buckets unless a verylarge rim chamber 11 were provided, which would have to be cut away at aloss in finishing the wheel, or unless alarge volume of the molten metalwere caused to flow'through the mold to insure uniform fluidity in therim chamber. This latter process is wasteful and uniform circulationuncertain. To provide an uniform circulation of molten metal of thedesired fluidity to insure the buckets being all properly heated andunited with the resulting wheel rim and to avoid premature chilling ofthe molten metal, I prepare the metal 1n the following manner. I placein a foundry ladle 12 a predetermined percentage of steel chips orfilings, then fill the ladle with the required amount of molten castiron and add any desired amount of molten nickel produced. preferably"by the thermit process in a ladle 13. After adding the nickel, atitanium thermit cartridge 14 is held under the surface of the fluid inladle 1 2 and the resulting reaction of the thermit thoroughly dissolvesthe steel chips and distributes the steel and nickel evenly throughoutthe metal in the ladle. At the same time i the fluidity of the ladlecontents is greatly increased with but little increase of tempera ture.-This highly fluid metal is now poured into the mold. throu h the runners15 and flows freely distributing itself evenly in the rim chamber 11 andflowing around the bucket ends and through their perforations. Anydesired number of risers 16 may be provided around the rim chamber orelsewhere toprevent initial cooling of metal at therim and also to avoidshrink strains or p1pmg. these-users to start a further reaction andkeep the metal liquid.

After the wheel 17 has cooled, it is removed from the mold and machinedafter Also thermit may be introduced in. r

which the buckets may be connected to a shroud or band 18 havingperforations through which the bucket stems 3 pass and are riveted overas seen in Fig. 5.

The nickel is used to give toughness and anticorrosive properties to thecasting while the steel imparts the desired strength.

It will be understood, however, that I am' not limited to any particularcharacter of metal for casting, and thatthe metal used may be brought toa high state of fluidity by the use of thermit or similar reactivechemicals or compositions.

Without limitation therefor to the detailed steps of the foregoingprocess which are given as illustrating the preferred manner of carryingmy invention into effect, what I claim as new and desire to secure byLetters Patent, is

1. An improved process for manufacturing turbine members, such aswheels, having buckets attached to the body .portions of said members bya cast joint, which consists in forming a mold for casting the body,said mold having buckets so mounted therem that the ends to be unitedtothe body project into the space in the mold which receives the metal,preparing a quantity of molten metal, increasing the fluidity of themolten metal by introducing a quantity of thermit or the like into saldmetal, and then pouring this fluid metal into the mold where itsurrounds the projecting endsof the buckets.v 1-2. An improved processfor manufacturing turbine wheels in the form of relatively thin diskscarrying a rim to which metal buckets are secured by a cast joint, whichconsists in forming a mold for casting the wheel, said mold havingbuckets mounted therein with the ends to be united to the wheelprojecting into the-rim chamber in the mold, placing a quantity of solidmetal in a suitable. receptacle, preparing molten metal and pouring iton the metal in the receptacle, introducing a titanium thermlt cartridgeinto the mass of metal in the receptacle to melt the solid metal andincrease the fluidity of the contents of the receptacle, and thenpouringthe extra-fluid metal into the mold where it surrounds the projectingends of the buckets. I

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

JALIES .WILKINSON.

Withessesf Gno. H. Carson, HENRY J. S'rrmns.

